A construction worker tried desperately to warn his brother-in-law that the awning on which they were standing at a Brooklyn job site was about to collapse – but his cries of danger came to late to save the man from plunging 45 feet to his death yesterday.

Edgar Jaramillo, 25, said the sound of cracking concrete told him tragedy was imminent – and gave him time to jump to safety from the weak metal structure on which he, brother-in-law Angel Gungasaca and two other men were standing while pouring concrete at a Bay Ridge condo development.

“I told everyone to jump but they didn’t hear me,” he said through a translator. “In one second, the balcony fell down.”

The 10 a.m. collapse of the awning at the back of the Marine Condominiums development project on Fort Hamilton Parkway in Bay Ridge killed Gungasaca – a 35-year-old immigrant with a wife and two children back in his native Ecuador.

It left the other two men seriously injured in the plunge from the four-story building. One of the injured men, José Fernandez, 21, suffered a foot injury, while the other, Gumyul Bac, was left with a head wound, officials said.

“It was more blood than I’ve ever seen in my whole life,” said worker Bekim Muriqi, 29. “[Gungasaca] bled, he bled from his nose and his mouth and then he stopped breathing.”

FDNY officials probing the tragedy said the awning on which the men were standing had a support beam improperly installed.